feat: improve AI chat - system prompt, tool output, context window display (#17769)

⚠️ **AI-generated PR — not ready for review** ⚠️

cc @FelixMalfait

---

## Changes

### System prompt improvements
- Explicit skill-before-tools workflow to prevent the model from calling
tools without loading the matching skill first
- Data efficiency guidance (default small limits, use filters)
- Pluralized `load_skill` → `load_skills` for consistency with
`load_tools`

### Token usage reduction
- Output serialization layer: strips null/undefined/empty values from
tool results
- Lowered default `find_*` limit from 100 → 10, max from 1000 → 100

### System object tool generation
- System objects (calendar events, messages, etc.) now generate AI tools
- Only workflow-related and favorite-related objects are excluded

### Context window display fix
- **Bug**: UI compared cumulative tokens (sum of all turns) against
single-request context window → showed 100% after a few turns
- **Fix**: Track `conversationSize` (last step's `inputTokens`) which
represents the actual conversation history size sent to the model
- New `conversationSize` column on thread entity with migration

### Workspace AI instructions
- Support for custom workspace-level AI instructions

---------

Co-authored-by: claude[bot] <41898282+claude[bot]@users.noreply.github.com>

packages/twenty-server/src/engine/core-modules/billing/billing.resolver.ts

@@ -23,6 +23,10 @@ import { BillingSubscriptionService } from 'src/engine/core-modules/billing/serv
 import { BillingUsageService } from 'src/engine/core-modules/billing/services/billing-usage.service';
 import { BillingService } from 'src/engine/core-modules/billing/services/billing.service';
 import { formatBillingDatabaseProductToGraphqlDTO } from 'src/engine/core-modules/billing/utils/format-database-product-to-graphql-dto.util';
+import {
+  INTERNAL_CREDITS_PER_DISPLAY_CREDIT,
+  toDisplayCredits,
+} from 'src/engine/core-modules/billing/utils/to-display-credits.util';
 import { PreventNestToAutoLogGraphqlErrorsFilter } from 'src/engine/core-modules/graphql/filters/prevent-nest-to-auto-log-graphql-errors.filter';
 import { ResolverValidationPipe } from 'src/engine/core-modules/graphql/pipes/resolver-validation.pipe';
 import { type UserEntity } from 'src/engine/core-modules/user/user.entity';
@@ -298,7 +302,17 @@ export class BillingResolver {
   async getMeteredProductsUsage(
     @AuthWorkspace() workspace: WorkspaceEntity,
   ): Promise<BillingMeteredProductUsageOutput[]> {
-    return await this.billingUsageService.getMeteredProductsUsage(workspace);
+    const usageData =
+      await this.billingUsageService.getMeteredProductsUsage(workspace);
+
+    return usageData.map((item) => ({
+      ...item,
+      usedCredits: toDisplayCredits(item.usedCredits),
+      grantedCredits: toDisplayCredits(item.grantedCredits),
+      rolloverCredits: toDisplayCredits(item.rolloverCredits),
+      totalGrantedCredits: toDisplayCredits(item.totalGrantedCredits),
+      unitPriceCents: item.unitPriceCents * INTERNAL_CREDITS_PER_DISPLAY_CREDIT,
+    }));
   }
 
   @Mutation(() => BillingUpdateOutput)

packages/twenty-server/src/engine/core-modules/billing/dtos/outputs/billing-metered-product-usage.output.ts

@@ -1,4 +1,4 @@
-import { Field, ObjectType } from '@nestjs/graphql';
+import { Field, Float, ObjectType } from '@nestjs/graphql';
 
 import { BillingProductKey } from 'src/engine/core-modules/billing/enums/billing-product-key.enum';
 
@@ -13,18 +13,18 @@ export class BillingMeteredProductUsageOutput {
   @Field(() => Date)
   periodEnd: Date;
 
-  @Field(() => Number)
+  @Field(() => Float)
   usedCredits: number;
 
-  @Field(() => Number)
+  @Field(() => Float)
   grantedCredits: number;
 
-  @Field(() => Number)
+  @Field(() => Float)
   rolloverCredits: number;
 
-  @Field(() => Number)
+  @Field(() => Float)
   totalGrantedCredits: number;
 
-  @Field(() => Number)
+  @Field(() => Float)
   unitPriceCents: number;
 }

packages/twenty-server/src/engine/core-modules/billing/utils/to-display-credits.util.ts

@@ -0,0 +1,9 @@
+// Internal credits use micro-precision: $1 = 1,000,000 internal credits
+// Display credits are 1000x coarser: $1 = 1,000 display credits
+// This mirrors the "micro" pattern in payment systems (e.g. microdollars → dollars)
+export const INTERNAL_CREDITS_PER_DISPLAY_CREDIT = 1000;
+
+// Converts internal (high-precision) credits to user-facing display credits.
+// Rounds to 1 decimal place for clean display (e.g. 7500 → 7.5).
+export const toDisplayCredits = (internalCredits: number): number =>
+  Math.round((internalCredits / INTERNAL_CREDITS_PER_DISPLAY_CREDIT) * 10) / 10;